1. Field of the Invention
The present invention relates to a method of initializing parameters in a programmable machine controller (hereinafter referred to as PMC) of a numerical control unit (hereinafter referred to as NC unit).
2. Description of the Related Art
Conventionally known is an NC unit which includes a PMC adapted for sequence control of various control sections, such as counters, timers, keep relays, etc. For some reason or other, in the NC unit of this type, it may happen to become necessary to initialize the values of various parameters during the operation of the PMC or change of these parameter values. Conventionally, however, this process of initialization must be executed by manual operation, which entails some trouble.
Generally, in the NC unit of this type, the PMC is furnished with a programmable machine controller-random access memory board (hereinafter referred to as PMC-RAM board) for debugging. After a debugging process using a memory unit carried by the RAM board, the PMC is loaded with a read-only memory cassette (hereinafter referred to as ROM cassette), so that memory contents, including PMC parameter values and stored in the memory unit of the RAM board, are transferred to and stored in a memory unit built in the cassette. In this state, the NC unit is shipped to be delivered to a user. Thus, the NC unit is operated with the ROM cassette therein and by utilizing the memory contents stored in the cassette. In initializing the PMC parameter values, moreover, the initial values of the various parameters, which are set by means of a manual setting section of the NC unit, are generally transferred to and stored in a separate RAM of the PMC through a predetermined transfer path. While the PMC is mounted with the PMC-RAM board, that is, during the debugging process, the parameters can be initialized with use of a parameter cassette or an initialization program based on the PASCAL language or the like.
As described above, the PMC parameters usually must be initialized by manual operation, and the capacity to cover all the parameter values is normally as large as 2K bits. Thus, the initialization requires a long time. Moreover, the conventional method, based on the manual operation as mentioned above, lacks in high-speed performance, whereas the initialization is often a matter of urgency.